Production of water gas



JJune 1l', 19410. R, RUMMEL "PRODUCTION oF WATER @As 2 Sheets-Sheet 1l'iled April 9, v1958 a MU SMN June11, 1940. R, HUMMEL y 2,204,003

rnonucwrou oF wmn @As Filed Aprilv 9, 19:59 2 sheets-sheet 2 PatentedJune ll, 1940 PATENT OFFICE PRODUCTION F WATER GAS Roman Rummel,Ruhland, Germany,assignor, by

mesne assignments,

to Kappers Company,

Pittsburgh, Pa., a corporation of Delaware Application April 9, 1938,Serial No. 201,193

In Germany 7 Claims.

The present invention relates to the production of water gas or the likefrom solid fuels especially from bituminous coals, by using a highlyheated mixture of steam and gases, preferably a part of the water gasproduced, for heating the fuel up to the temperature of the water gasreactlon,said mixture serving as a heat carrier and I shallterm the saidmixture in this description as heat carrier.

In order to produce water gas or the like from fbituminous fuels, ashaft furnace is employed which is traversed by the fuel from the topdownwards. In various zones of the shaft. there have been provided meansfor introducing gases into the shaft and/orfor withdrawing gases fromthe shaft. Contrivances for heating up the gases, for instanceregenerators, such as of the Cowpersystem well-known for heating-up theair of blast furnaces, are connected with the shaft. The heat carrier,i. e., the mixture of gas and steam, heated-up in these -contrivances,is in-` troduced into the shaft and extracted lfrom thel shaft in Vsucha manner that the fuel on its way from the top downwards is brought into`contact with the hot heat carrier and is heated thereby gradually,reaching finally that temperature at which the steam reacts with thecarbon of' the fuel with the formation of a mixture of carbonio acid,carbon monoxide, hydrogen and other constituents, such mixture being theso-called water gas.

When the bituminous fuel, for instance brown coal, lignite, shale or anyother suitable coal, is charged into the shaft, the fuel is first vdriedand degasifled in the upper part of the shaft, analogously to thewell-known coal distillationv process. As soon as the fuel is heated toa sufliciently high temperature, the reaction of carbon with steambegins. The upper part ofthe shaft is, there- 40 fore, called by me thedegasication zone and the lower part is termed hereinafter as gasifylngzone. The exact position of both these zones, whichunder certaincircumstances are not sharply separated from each other, especially whentreating reactive fuels, depends on the working conditions, inparticular on the temperature of the heat carrier and the position ofthe inlets April 10, 1937 duce the water gas or the` like in continuousoperation. If regenerators areemployed for heating-up the heat carrier,it issof advantage to provide several of such regenerators and 'toconnect them in alternation, by means' of suit- 5 able shut-off andreversing valves, with the gas producer shaft in such a manner -thatcontinuously a hot heat carrier from one regenerator or from severalregenerators is introduced into the gas producer shaft.

In many instances, it is desirous of obtaining the water gas, free fromhydrocarbons which are formed during the degasiiication of thebituminous fuels. For the synthesis `of valuable hydrocarbons fromhydrogen and carbon monoxide 15 in the presence of certain catalysts,containing nickel or cobalt or other substances, it is a requirement,for instance, that the gas be one which is free from such hydrocarbonswhich, similar to the tarry constituents formed at the 20 degasicationof bituminous fuels, tend to deposit on the surface of the catalysts,which will thereby become ineffective or at least less effective.

In order to produce by means of a heat carrier a water gas; free fromall such hydrocarbons, 25 by means of a heat carrier a part of theheatcarrier and of the newly developed water gas may be extracted from thegasifying zone of the gas producer shaft at such a point where the fuelis already fully degasified, i. e., practically free 30 from bituminousmatter or where the fuel is degasifled at least to such a degree thatthe remaining'hydrocarbons decompose at the temperatures existing in thegas producer. The remaining part of the heat carrier and of the fresh-35 ly made water gas, which is not withdrawn from the gasifying zone ofthe gas producer, flows upwards through the degasiiication zone of thegas producer and gives olf its heat to the fuel which is thus distilled.40

A considerable disadvantage of the'before dex scribed process consistsin that the heating-up of the fuel to the water gas reaction temperatureand the gasifying of same takes place in one single` zone. Thereby. thetemperature of the 45 heat carrier after entering the gasifylng zone,drops very quickly and the water gas reaction takes place slowly.Moreover, the fuel undergoes a secondary degasification by `its beingheated in the gasifying zone, whereby alsofthe hydro- 50 carbons arewithdrawn into the useful gas, notwithstanding the fact that the watergas necessary for the synthesis process should, however, be free fromall tarry hydrocarbons, if possible.

An essential object of my present invention is to provide suchimprovements of the described method of water gas production which willovercome the before mentioned disadvantages and attain otherimprovements as hereinafter more particularly set forth and described.

Principally, my invention consists in introducing two separate heatcarrier'streams into the gas producer, of which the one stream mainlydegasies and preheats the fuels, and other stream gasifies, wholly orpartly, the degasifled and preheated fuel in the presence of steam.'I'he heat carrier in this manner, enters the degasification and thegasifying zones respectively preferably at an equal temperature and isled into the gasifying zone in co-current and into the degasication zonein counter-current, to the direction of movement of the fuel movingwithin the gas producer shaft from the top downwards. In this manner,the fuel reaches the gasifying zone at approximately the sametemperature as the heat carrier. 'I'he sensible heat of the heat carrierand of the fuel is utilized for the formation of water gas. Since thefuel enters the gasifying zone in hot condition and is subjected to nofurther temperature rise, after it-reaches the water gas reacticn'zonethen no secondary degasification of the fuel occurs, whereby nohydrocarbons enter the synthesis gas, as occurs with the old process inwhich the heat carrier when hottest first meets the hottest water gasreaction zone, instead of as here wherein the heat carrier when hottestfirst meets the fuel in advance of its entering the water gas reactionzone, thus giving up its highest specific heat in preheating the fuel asit is about to enter the water gas reaction zone before the endothermicreaction takes place. In this' manner, the fuel just abovey the watergas reaction zone is more highly preheated to closer the 'reaction'temperature before entering that zone, and the heat carrier is cooledsomewhat of its excessive heat before reaching the endothermic water gasreaction zone. Consequently the water gas reaction is made to take placemore rapidly and chance of secondary degasification avoided.

Furthermore, the present invention contemplates and makes it possiblefor the admission of steam, necessary for the productionof water gas,into the gasifying zone, and if necessary directly into thedegasification zone of the gas producer, and it comprehends theutilization of the sensible heat of the fuel residue for the additionalproduction of water gas. Figure 1 of the drawings shows schematically anexempliflcation of the process according to the present invention.

Figure 2 shows schematically a gas producer `in which the steamnecessary for the production of water gas is introduced into thegasifying zone and the sensible'heat of the fuel residue is led back tothe gasifying zone by means of steam fo the additional production ofwater ga's.

The fuel is discharged Vfrom the storage hopper I (of Fig. 1) by openingthe slide 2 into the reservoir 3, from where it is delivered through acontinuously or intermittently operated feeding de- .vice 4 to the gasproducer 5. The gas producer 5 is illustrated on the drawings as ashaft-furnace. ,For the supply of the heat carrier, there have beenprovided several bridges 6 by which the h eat carrier is uniformlydistributed over the cross section of the shaft. Above these bridges issituated the degasification or preheating zone a, underneath the bridgesis the gasifying zone b.

The highly heatedmixture consisting of heatv carrier and steam, entersthe shaft of the ,gas producer below the bridges 6 and separates hereinto two streams. The rst heat carrier stream is passed through the zonea, where it distills, and as its temperature lowers it then, at lowtemperature, dries and preheatsthe fuel, by givingoff its sensibleheat.The' second heat carrier stream is led through the zone b in which liesthe fuel which was heated previously in the zone a. Under the influenceof thel steam from the heat carrier upon the glowing fuel, water gas isproduced in the zone b. 'The water gas together with the heat carrierleaves the shaft of the gas produced through the bridges 'I. The fuelresidue below the bridges 1 is now for instance indirectly cooledin theboxes 8 through which water is led. It is then delivered by means of thecontinuously or intermittently operated feeding device 9 from the gasproducer into the container I0 from Where it is discharged into cars;

i low temperature distillation gases as well as the steam generated fromthe water content of the fuel, flow along together with the heat carrierpassing through the zone a, and leave the gas` producer through the gasoutlet I3, and are delivered through the pipe line I4 into the detarrerThe blower I6 sucks-off the tar-free gas and delivers it to the heaterI'I for the gaseous heatcarrier, Where it is raised to the necessarydegree of temperature. Here, a cracking and conversion of hydrocarbonsoriginating from the lowtemperature distillation gases, takes place bymeans of steam. 'I'hen the heated gaseous heatcarrier is led through thepipe line I8 to the bridges 6, whence it reaches again the gas producershaft. The steam necessary for the production of water gas and for theconversion of hydrocarbons isadded to the gaseous heat-carrier beforethe heater I1 through the pipe line I9, or behind the heater' II throughthe pipe line 20, or* through both.- The temperature of thel gaseousheat-carrier can hereby be controlled extremely well.

The gaseous heat-carrier that is passed through the zone b and the watergas produced in this zone, leave the gas producer shaft through thebridges I as the hydrocarbon-free nal water gas, and ow through the pipeline 2| to the heat exchanger 22, where they transmit the greatestamount of their sensible heat. The heat exchanger 22 is constructedpreferably as a wasteheat'boiler in which the steam necessary for theproduction of water gas is generated. Then the gases are delivered to acooling and cleaning plant consisting for instanceof a precooler 23, ame-A chanical gas purifier 24 and a final cooler 25. The blower 26 sucksthe gas from the cleaning plant and delivers it lto the pipe line 21which leads to the places of consumption.

The heat carrier streams are controlled through the blowers I6 and 26.So much of the heat carrier is introduced into the degasification zonea, as is necessary for the distillation, lowtemperature process, dryingand preheatment of the fuel. 'I'he heat carrier together with thelow-temperature distillation gases, as well as the vapours and the watergas produced within the range of high temperatures in zone a, leaves thegas producer through the gas outlet I 3 at a tem- If the fuel is not tobe gasiiled completely, but

perature 'lying labove the dew point'of the gas so that the steamcontained in the' gas does not condense. In the gas heater I1, the4gases are heated-up to such an extent that a'cracking and conversion ofthe hydrocarbons from the .low

rtemperature distillation gases takes place `in reaction with steam.'I'he heat carrier enters the gas producer through the bridges 6 at atemperature necessary for the water gas '.process. This temperaturemainly depends on the reactivity of the coke lying underneath thebridges 6, and on the composition of the water gas to be produced. 'Ihequantity of heat to be utilized for the reaction of the water gasprocess in the zone bis taken from the heatcarrier passing through thiszone and lpartly from the heat stored in preheated coke when it reachesthe zone b, so that both media are cooled-down by the endothermic watergas reaction. 'Ihe eect of the temperature drop in the zone vb isdetermined by the composition of the water gas to be produced. Theinletand outlet temperature of the heat carrier of thezone b is. therefore,predetermined and fixed for the composition of `water gas that is to bemade and for the kind of fuel that is to be used. The quantity of thisheat tillation gases, which are cracked in the heater and converted,since the quantity of the heat carrier passing through the zone a, mustbe main-V tained permanently. This latter quantity"` may 'be controlledby the heat carrier blowers and' is determined by the heat quantity tobe utilized in 'the zone a. for the production of water gas as well asfor the low-temperature distillation treatment,

` the production of water gas according to the- Gil drying andpreheating of the fuel. Therefore,

present invention may be also carried out in the zone a, whereby thetemperature drop in the zone 'b can be altered correspondingly. Byregulating the heat-carrier temperature and by altering the two heatcarrier streams, water gas of any composition can be produced from allkinds of fuel. The fuel must, however, be such as to allow for thepassage ofthe heat carrier. 'Ihe fuel, therefore, has to be oflumpy-size, i. e., ney grained fuel must be briquetted before being useY Another mode of carrying out the process according to the presentinvention is shown in Figure 2. The heat carrier is delivered throughthe pipe line I8 to the bridges 6, separates within the i gas producer 5below the bridges into two streams as above described. If now a fuel ispre-treated in the zone a for the'production of water gas, which fuelhas a high percentage of moisture and requires a great amount of heatfor its drying and low-temperature distillation, it is more advantageousto carry out the water gas production only in the zone b. For thisreason, another set of bridges 28 are also for instance arranged in thezoneb.' Steam only, for the production of water gas is admitted throughthe bridges 28 to the zone b, said steam together with theheat carrierfrom bridges 6 flows to the bridges 1 and on itsway thereto it isconverted to water gas with the glowing coke-carbon. In order to avoid arapid and considerable drop of temperature in the zone b, the steam issuperheated to the temperature existingin the zone b, which for instancecan be arrived at by a superheating pipe coil 29 which is arranged inthe heat carrier pipe line I8.

if a. certain quantity of coke is still to be left ungasiled to berecovered for heating the heat carrier, it is of advantage to make useof the sensible heat stll contained in the residue of coke leaving thezone U, to obtain an additional production of water gas. the cokeunderneath the bridges 'I in countercurrent to the fuel. Said steamtakes the heat from the coke, superheating the steam and lateron beingutilized in the reaction for the formation of water gas. The steamsuperheating process takes place in zone c of the gas producer shaft.The saturated or somewhat superheated steam ows in at point 30 in thebox 3l which is in connection with the shaft zone c through the slots32. The steam enters the zone c through the slots 32 and flows to thebridges 1. In this way, the coke is cooled-down and the steam issuperheated until it has reached the degree of temperature necessary forthe water gas reaction with coke in the portion of the fuel bed underthe water gas reaction zone. The water gas thus developed is withdrawn,along withthe water gas leaving the zone b through the bridges 1.

By the separation of the heat carrier stream Within the gas vproducer asaforesaid, the cross section load of the gas producer is considerablyimproved, since the preheatingand the gasification of thefuel areseparated from one another. The capacity based on the cross-section ofthe furnace is therefore larger than with the known processes. Thesensible heat of the fuel residue is utilized in the gasifying zone forthe water gas' reaction. Therefore, also the heat required for thecarrying out of the process willbec'ome less. Moreover, the quantity ofheat carrier circulating is hereby reduced.

Any kind of fuel may be used for the treatment.

Even wholly or partly degasified fuels allow for advantageousgasification, if carried out according to my` present invention. In thiscase, the fuel in the zone a is mainly preheated to-'the temperaturerequired for the production of water gas. It is also possible to performany desired stage of the water gas production within the zone a. Thesteam herefor may be added to the heat carrier before entering the gasproducer or by the introduction of steam into the zone a, i. e.,

through the bridges similar to the' kind described before in connectionwith zone b, the heat carrier passed through thezone a being returned tothe gas producer. By carrying out the gasification partly in the zone a,a uniform'cross section load across the entire height of the gasproducer shaft can be attained which is of special advantage `with thosefuels which require for their gasification and preheating a smalleramount of heat than for their partial and full gasification ln thegasifying zone b.

Accordingly, the highest efciency can be arrived at with the presentinvention, because of the full utilization of the entire space of theshaft.

Another exemplification of the process according to the presentinvention consists in leading both heat carrier streams separately intothe gas producer shaft. Thereby, it is rendered pcssible to let thementer the degasiiication zone and the gasifying zone at adiilerenttempexiatures, which permits a further control and adaption tothe gasifyng fuel. Furthermore. steam may be added to each heat carrierstream for a denite production of water gas in either or in both zones.

Steam is passed throughy a components.

If a synthesis gas is to be produced which, in additionvto the water gasconstituents, still contains other gases, they can be added to the heatcarrier stream, according to the present invention, either outside thegas' producer or inside the gas producer, in the gasifying zone, or inthe degasication and preheating zone. For example, during themanufacture of a synthesis gas containing nitrogen in the gasifyingzone, air is introduced. The oxygen of the air combines with the carbonof the fuel mainly to form carbon monoxide, whereas the nitrogen of theair leaves the gas producer as an inert gas, together with the gasesresulting from the gasifying zone. The gas mixture leaving the gasproducer `is led, if required, to a conversion plant in order to reduceall undesired gas constituents into synthesis gas If a high content ofcarbon monoxide is required to be produced by the heat carrying gas,which cannot be attained even with a hot run of the water gas process,then oxygen is, for instance, added to the heat carrier stream in thegasifying zone. Thisaddition of oxygen effects a gasification of thefuel to carbon monoxide, whereby an enrichment of the heat carrying gaswith this gas takes place.

Furthermore, it is possible 4to maintain the composition of the heatcarrying gas by the introduction of foreign gases into the gasifyingzone. In the presence of glowing fuel and reactive gases, said gases arecracked or converted in the heat carrier. By this means or by any othercombination suitable for the special case, it is possible to obtain anydesired composition of heat carrying gases within the utmost limits,

quite independent of the kind of the fuel used.

1 have now described in the foregoing my present invention on thelines'of a preferred embodiment thereof, but my invention is not limitedin all its aspects to the mode of carrying it out the water-gas reactionzone; and effecting said maintenance of the zones of the fuel bed bytraversing the upper predistillation zone with a preheated gaseous heatcarrier medium of watergas and circulation of the same from the upperpredistillation zone together with hydrocarbons therefrom and steamthrough a separate heating-up stage to reheat the medium and thence backto the fuel bed through the lower water-gas reaction zone for thewater-gas reaction therewith; the improvement comprising: introducingthe gaseous heat carrier medium for the upper predistillation and lowerwater-gas reaction zone to the bed intermediate the respective zones,and in quantities for the respective zones to supply the heatrequirements for the respective zones; withdrawing the hydrocarbon-freewater-gas from the fuel bed at a zone intermediate the lower water-gasreaction zone and the region of withdrawal of solid residue from belowthe watergas reaction zone; the heat carrier for the respective zonesbeing introduced-to the fuel bed at a region in which the stream dividesand the part for the upper zone traverses the upper zone independentlyof the lower zone and the other part of the stream for the lowerwater-gas reaction zone traverses predistilled fuel from the upper zonebefore the predistilled fuel and the heat carrier reaches the lowerwater-gas reaction zone.

2. A method as claimed in claim 1, and in which the heat carrier streamfor the upper predistillation degasifying zone is led countercurrentthrough the fuel therein, and the head carrier stream for the lowerwater-gas reaction zone ls led co-currently through the fuel of thewaterl gas reaction zone.

3. A method as claimed in claim 1, and which includes the step ofgenerating part of the watergas also in the upper predistillationdegasifying zone.

4. A method as claimed in claim 1, and in which steam for water-gasreaction is injected directly into the fuel bed in the lower gasifyingzone but above the lower oiftake for hydrocarbon-free water-gas.

5. A method as claimed in claim 1, and in which steam necessary for thewater-gas production is added to the heat carrier after it leaves theheating-up stage but before it enters the fuel bed,

- whereby part of the water-gas is generated also in the upperpredistillation degasifying zone.

6. A method as claimed in claim 1, and in which additional steam is alsolled through the fuel residue in the region of the bed underneath thezone of withdrawal of hydrocarbon free water-gas, said steamtransferring sensible heat of the fuel residue upwardly toward the lowerwatermedium that is to react in the lower water-gas reaction zone.

ROMAN RUMMEL.

